Control device and system



y 1954 H. A. ALEXANDERSON ETAL 2,678,642

CONTROL DEVICE AND SYSTEM Filed May 29, 1945 5 Sheets-Sheet l lNV E NTOR5 a l-louqrd AAlexaadersaz,

Rob 2. H

gt ague TTORNE H. A. ALEXANDERSON ET AL ,678,642

May 18, 1954 CONTROL DEVICE AND SYSTEM 5 Sheets-Sheet 2 Filed May 29,1945 I l I I y 8, 1954 H. A. ALEXANDERSON ETAL 2,678,642

CONTROL DEVICE AND SYSTEM Filed May 29, 1945 5 Sheets-Sheet 3 I'ILLDZQQ75 P 3 HQIVENTORS Robert Z.H ue BY 9 27/ ATTORNEY VIoward A.Alexalzdersola y 18, 1954 H. A. ALEXANDERSON ET AL 2,678,642

CONTROL DEVICE AND SYSTEM Filed May 29, 1945 5 Sheets-Sheet 4 INVENTORSRebel-i Z Hague.

ATTORNEY May 18. 4 H. A. ALEXANDERSON ET AL 2,678,642

CONTROL DEVICE AND SYSTEM Filed May 29, 1945 5 Sheets-Sheet 5 IN VENTOR5HowardAA/zxarzdefsom BY Robe/'1' Z Hague.

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ATTORNEY Patented May 18, 1954 UNITE D STATES TEN T O FFICE CONTROLDEVICE AND SYSTEM Howard A. Alexanderson, Wood-Ridgaand Robert Z. Hague,Oradell, N. 5., a's'signors to Bendix Aviation Corporation, Teterboro,N. J., a corporationof Delaware 35 Claims. (Cl. 123-403) The presentinvention relates to improved control devices and systems for the powerunits of aircraft, particularly of the supercharged internal combustionengine type arranged for driving an automatically controlled Variablepitch propeller.

An object of the present invention is to provide a novel. and improvedcontrolmechanism for an aircraft'engine, which provides meansfor'eifecting simultaneously, selection of engine R. P. lVL: selectionof the intake manifold pressure of an internal combustion engine, andnovel means for modifying the relationship between engine R. P. M. andmanifold pressure in the cruising power ranges for the bestfuel economy.

Another object of the invention is to provide a novel engine throttlecontrol operable to maintain a preselected intake manifold pressure andincluding means operable upon the throttle being adjusted to its maximumopen position to control the speed of a supercharger so as to maintainthe selected intake manifold pressure.

Another object of the invention is to provide novel manually controll dmotor means for positioning an engine throttle valve.

Another object of the invention is to provide means for effecting directmanual control of the throttle upon failure of the normally operativemotor system for controlling the throttle.

Another object of the invention is to provide a novel hydraulicfollow-up mechanism for changing the selected intake manifold pressureupon change in the supercharger speed so as to maintain stability ofcontrol.

Another object of the invention is to provide a novel hydraulic controldevice for eifecting'intake manifold pressure through sequentialcontrolof the throttle and supercharger speed.

Another object of the invention is to provide a novel follow-upmechanism including means for effecting rapid acceleration of thesupercharger. speed upon a great increase inthe intake manifold pressurebeing required to meet the selected pressure.

Another object of the invention is to provide novel means for effectingsequential control of a supercharger from a low speed hydraulic drive"to a high speed hydraulic drive.

Another object of the invention is to. provide novel hydraulicallyoperated means for controlling the intake manifold pressure of anaircraft engine.

The above and other objects and: advantages of thepresentinventionwi'll' appear more fully here-= inafter from aconsideration of the detailed de scription which follows, taken togetherwith the accompanying. drawings wherein the features of the presentinvention are illustrated. It'i's't'o be expressly understood, however,that the drawings. are for the purpose of illustration only and. are notdesigned. as a definition of the limits of the invention.

In the drawings wherein like reference characters refer to like partsthroughout the several views:

Figure l. is. a diagrammatic view of the novel hydraulic control system;I

Figure 2 is a diagrammatic view of partof the control mechanism shown inFigure 1';

Figure 2a is a diagrammatic view of a second part of the. controlmechanism;

Figure 2b is a diagrammatic view of a third part of the controlmechanism; and

Figure 3 is an enlarged view of the pressure reset mechanism.

Referring tothe drawings there is provided inv the present. inventionamainpilots control lever l, which. is connected by a link Zto anoperative control lever 3. As shown in Figure 2 ,the control lever 3 iskeyed to a main control shaft 4 which extends into the maincontrol unitvindicated in Figure 1 by the letter A and shown diagrammatically inFigural Driven by shaft 4 is a propeller pitch governor selectormechanism indicated generally by numerals-and including an arm 5 keyedat oneend to the shaft 4' and pivotally connected by alink l to an. arm8 rotatably mounted on a shaft 9 eccentrically affixedto one end of anadjustable pin: it. The pin it is moimted' in a casing of the unit Apart of. which is shownat IDA.

There is further rotatably mounted. on the: pin it an arm ii..- Thearm Mis bent'at an acute angle. at 12" and pivotally connected to one end ofa link Hi. The arm II- is connected to arm 8 by an idler shaft I3; Theidler shaft [3- extends from points intermediate the opposite ends ofarms ii. and 8 and is affixed eccentrically toa cam its. rotatablymounted in mm H.-

The other end of link M. is connected. to an arm [5 which is keyed toone end of a tubular sleeve lt-rotatably mounted on the shafts. Theopposite end of thesleeve it is keyed to a. pulley l'l. which as shownin Figure 2 is drivingly connectedthrough: lines i8- toan operatingpulleylit for adjusting a propeller pitch: governofcom trol indicatedgenerally by the numeral. 20:.

The latterpropeller' pitch governor control may be of a: suitable typewell knownin-the art; The same is shown in Figure 1 asbeingofatypehaving the operating pulley l9 mechanically connected to a gear2! and rack '22 for adjusting a governor spring 23 and fly-weightgovernors 24. The fiy-weights 24 are pivotally mounted at one end of ashaft 25 drivingly connected through suitable gear means (not shown) toa drive shaft of an aircraft engine indicated by the numeral 26.-

Slidably mounted in the shaft 25 is a valve 2'! of conventional type,adjustably positioned under tension of the spring 23 and thecounter-acting biasing force of the centrifugally actuated fly-weights24. The valve 21 is arranged to control the operation of a piston notshown which controls the pitch of a propeller 23 driven by the engine 26in a manner well known in the art.

Thus the engine speed or R. P. M. of the engine 26 may be adjusted byvarying through the pulley line IS the tension of the governor spring 23and the resultant position of the pilot valve 2'1. Moreover through thepropeller pitch selector mechanism indicated by numeral the relationshipof pilots control lever 1 travel to propeller pitch governor drivetravel may be modified by adjustment of the eccentric pin it toaccommodate production variations in the angular travel of propellergovernors 29.

The engine '26 also drives through a shaft 30 and a two speed hydrauliccoupling 3! a supercharger 32.

The coupling 3! includes a gear 33 keyed to the shaft 3 3 and drivinghigh speed coupling gear 34 and low speed coupling gear 35.

The high speed coupling gear 3 1 drives through a shaft 35 rotatablysupported by a bearing 31 one set of blades 38 of a hydraulic coupling39 of conventional type. The opposite cooperating blades 46 of thecoupling 33 are fastened to a driven shaft 41 rotatably supported by abearing 42. The shaft 4! has a fluid inlet passage 43 leading into thecoupling 39 for a purpose to be explained hereinafter. There is furtherprovided in the fluid coupling 39 a fluid outlet port Q6 through whichthe hydraulic fluid may be returned from the coupling 39 to a suitablesump not shown.

Keyed to the driven shaft 4| is a high speed gear as which drivesthrough gear ie the drive shaft ll! of the supercharger 32.

The low speed coupling gear 35 drives through a shaft 48 rotatablysupported by a bearing 39 one set of blades 58 of a hydraulic coupling55 of similar type to coupling 44 and having fluid outlet ports 5 IA.The opposite cooperating blades 52 of the coupling 5| are fastened to adriven shaft 53 rotatably supported by a bearing 53A. The shaft 53 has afluid inlet passage 54 leading into the coupling 5|. The latter passageis controlled by a valve 54A of a type arranged so that when the drivenshaft 53 rotates at a speed greater than the driving shaft 58 thepassage 56. is closed for a purpose which will be described hereinafter.The coupling and valve may be of a type described and claimed in U. S.Patent No. 2,400,307, granted May 14, 1946 to L. S. Hobbs et a1. andassigned to United Aircraft Corporation.

A conduit 55 leads from an airscoop through a carburetor 57 into the airinlet for the supercharger 32. A conduit 58 leads from the air outlet ofthe supercharger 32 to the intake manifold of the engine 26. A throttlevalve 59 controls the air inlet conduit 56.

The throttle valve 59 is controlled by a rod 60 operably connected, asshown in Figure 2b, to a throttle control arm BI.

The throttle control arm 6| is keyed to a shaft 62 rotatably mounted ina bearing formed in the casing of the control unit as indicated at 63.Rotatably mounted in the shaft 62 is one end of the shaft 4.

There is provided a servo piston 64 for operating the throttle 59through shaft 82. The piston as is slidably mounted in a cylinder 65having fluid pressure inlet passages 68 and 61 opening at opposite sidesof the piston 64.

The piston 64 has a piston rod 68 pivotally connected at one end to thepiston 64 and at the opposite end pivotally connected to an operatingarm 69 formed integral with the rod 62.

Keyed to the pilots control shaft 4 is a second arm 19 connected througha link H to one end of a walking beam 72. The opposite end of thewalking beam 12 is connected through a link 13 to the arm 69.

Pivotally connected at a point intermediate the opposite ends of thewalking beam 72 is one end of a lever arm 14 which is afiixed at theopposite end to a shaft 15.

The shaft '55 is rotatably supported in bearing portions 16 and '51formed apart of the control unit. Freely rotatable on the shaft 15 is anarm '58. The arm 18 is pivotally connected at the free end to a rod '19which connects the arm 8 to a piston 80. The latter piston 30 isslidably mounted in a cylinder 8| into which opens at one end a passage82 leading to a fluid pressure line such as oil under engine pressure.The piston 86 is normally forced under pressure of the oil in an upwarddirection as viewed in Figure 2b.

A spring 83 is positioned between the piston and the upper end of thecylinder so as to force the piston in a dowwnard direction upon oilpressure failure, whereupon the arm 18 is forced in a clockwisedirection. An adjustable screw 84 projects through the arm 18 and isarranged so as to engage an abutment plate 85 on the arm E5 in thelatter event so as to restrain movement of the arm 74 in acounterclockwise direction. A stop pin 86 projects from a portion 8'! ofthe casing of the unit so as to restrain the arm 14 from movement in anopposite direction.

The pilots control lever may then effect manual control of the throttlevalve 59 through shaft 4, arm Hi, link H, walking beam 72, link '13, arm69 and throttle control shaft 62.

The aforenoted manual control feature is described and claimed in U. S.Reissue Patent No. 23,490 granted May 20, 1952 to Howard A. Alexandersonand Robert Z. Hague and assigned to Bendix Aviation Corporation.

The adjustable screw 84 is preferably adjusted so as to permit a smallamount of angular travel of lever 74 between screw 84 and stop pin 85.During such manual operation of the throttle 59, lever arm 74 is drivenbetween its restraining stops 8 and 8G rotating shaft 75.

At the opposite end of the shaft 15 there is affixed an arm 88 throughwhich projects an adjustable screw 89. The screw 89 is arranged toengage a pin 99 which projects from an arm 9|, supported on shaft 75.The arm 91 is freely rotatable on the shaft 15 and includes a second pin92 which projects therefrom into a slot 93 formed in an arm 84 freelyrotatable on a pin 95 projecting from one end of a shaft 98. The shaft95 is rotatably supported in a bearing 9? formed apart of the casing ofthe control unit A.

The arm 94 has an abutment plate 99 which bears upon one end of aplunger 500 slidably supported by bracket portions [ill and biased in annwai'ddirection by-spring: IIl;2;.. Lever, arm Qkis dpipen: by pin 32?or; arm; 9I= so; as tomove plunger:

IMF;

The plunger it}! is; arranged. so as to. operablycontact at I102 one:end of. avalve stem. me which issbiasedunder force of; a. leaf spring;limrzinanup ward; direction. The valve stem mehas: valve: members tiltand. Hit; arranged; was to control. passagesrsfi andE-fi respectivelyopening intovalve chamber; till? and: leading: to chamber 65 at ops--positersidesiofpistonfi so as to controlthe. movement of the pistonfit;The fluid pressureline: 82: opens mtermediatathe openings of passages6.6. and 6;]:to valve: chamber It]; A fluidmediumioutilet or drainpassage. 1:518; alsdopenszfromrthez valve: chamber 8'13 at; the. upper:and lower sides; or. valves [.4151 and H respectively:

Another valve. chamber lI-Br is provided sepa rated; from the valvechamber I01 by a.. sealing member II I. Projecting through the sealingmember liJli a valve stem. H2. At thelower end ofz'the valve stem H2. ismounted acylindricalvalve H3 having a spring H whichrten'ds to bias:thevalve I13 stem: M2; inan upwardidirection.

The: fluid pressure passage 82' opens into. the valve chamber. Hit atthe upper sideof the-valves l l'iiisovthat during normal operation thefluid pressure-medium forces the valve H3 downwardinto the: positionshown in Figure 2a; The exhaust passage. l fifi has a port l l'5openinginto the housing of the control unit Av and a port Ilt opening into-thechamber i Illbut closed by the valve H 3 when biased downward to theposition shown-in Figure 2a. A maindrain passage lll opens into thevalve chamber H 6. During normal operation the fluid. medium. drainedfrom: the housing by suitableiports notshown'.

When no: pressure medium is. available or upon oil'- pressure failurethe drainvalve II3- which is loaded. by. spring. I! an moved inanupward. direction. under force of the spring H' l serving two purposes.Inca-uses the oil in the housing of: the controlv unit A to drain. to apredetermined low level. by; uncovering. a drain port. litisozasto pormitl sucndrainage through port I I5, passage I08; port: il.2i,=.va1vechamber 5 It. and throughpassage II? to the fluid: outlet. Secondly thespring Hill urges valve stein I i2gupward'into contacting relaition.with the: lower. end of the valve stem. H33 sovastoactuatethe valve stemHi3 in'anupward: direction;

During such fluidpressure failure, movement ofthe pilots-cont'rol leveri so as to move arm 10 in a counter-clockwise directioncausesmovement'in a counters-clockwise direction of'thelever arm- E lbetweenits restraining stopsSB and Stwhereupon valvestem H2: under forceof spring IIScauses servo-valveto move from its neutral position asshown in Figure 2a, to an upper position so as-to uncover the portsleading to passages 66 and 61' so-asto permit movement of the throttle-58 manually; Similarly uponmovement ofthe lever arm Wins. clockwisedirection between its restraining stops 85 and 85 as upon manualmovement of" arm Hi in a clockwise-direction lever arm 94 actuatwthroughplunger iilfi the valve'stem H13 in a downward direction openingtheports topassages tt-and'ti. It will be seen from theforegoing that themanual operation of the servo valve: H33 not only-permits the opening ofthe.

passage-thand else that the manual operation of arnriia and accordinglythrottle fitmay'beef fected, but in the event slight pressure be"available-suchmovement"ofthe 'valve I 03' directs such 6*? slightpressuree sofas; to: effect; piston ti t; so: as: assist the. manualmovement of. the" arrm t'ili'amis thereby assist in. the; manual controlof throttle valve 59?. Automatic control. of throttle.

When fluid pressure-is available in excess ora predetermined; value;the. piston 80: is moved upward under the pressure mediumfrom passage 82against, the forceoi spring 83. This latteriacti'om forces linkTSupward'movihg lever T8 in a counter-clockwise directionso astopermitleverflar-mr l lto move free of the restraining screw 81. Likewiseuponsuchfiuid pressure, medium becoming;

. effective thevalve I 53113 moved downward. against. spring I'Iijpermitting, the servo valive IE3 tomove free of the valve stem. H2under automatic. (1011:"

trol.

In order to effect. the. latter automatic. control.

: there. is. provided a. pressure. responsive bellowsl assemblyincluding. anevacuatedbellows- I21: sup;-

ported. atone endi by astud. I22 car-riedby. apontion .I 23' of .thecontrol .unitA.

Aspring IZ-tis positioned within theevacuatedv .bellows I21 tendingtoleXpa-ndthe same. A's-the:

' opposite end of. the bellows I2! there isprovidedt a movable plate.[25 interposed betweenthebele lows IZll anda secondbellows 26. Thebellows I26, is. mounted at the. opposite. end-bya. portion.-

. I2l-0frthecontro1 unit A. An adjustablepin I28, projects into thebellows IZGfI-omrtheportion, k251iso as to limit the extent ofcontractmn of. the: bellows 26 for a purpose, which w-illibe describedhereinafter.

A passage I29 formed: in: the control. unit. leads from the interior. ofthebellows I26 to) an conduit I30, shown EigureZlL The conduitsl3.0,.asshown in Figure. 1, leadsrtoithe ain intake. manifold conduit58. Thus the bellows I26; is: controlled by the. intake, manifoldpressure: of the enginerZE.

The-movable plate I25 between the manifoldpressure bellows 1'23 and;evacuated bellows L24. is connected through'a link: lsl leaf spring-1I323 beam. I33 and the leaf; spring i04- to:- the: senvo valve. I03;ing: of. Figure 2a. contains at opposite-ends the preloaded leaf springsHltl and. I32- whichfpermitr; deflection of. the servo valve i 03 byplunger NHL: and valve stem. H2. without excessively. loading-.. the:vbellows assembly. The. beam I33- mayhove v ever be made in the form of asolid beam. and.

link I3I provided with a preloading; mechanism which maintains the linkI31 at a fixed length.

The selected pressure or datum of the" bellows assembly" may be-changedbymoving a pin IN.

on which beam I33 is pivotallysupported. Pin; H4 is adjusted throughoperation of a whiflie tree. typeof'beam. I35 controlled throughoperation: of a pressure selecting mechanism',.a cruise shiftedin a.clockwise direction whereupon the servo valve Ifl3i will be adjustedupwardcausin'g;

a pressure medium to be applied through the. passage BB'tothe upper sideof the piston Stand;

exhausting the lower side through passage 611, This action willicausetherpiston tsvtobeadjusted I downward so as to adjust the-arm 69..andjarm'f.

Si in a counter-clockwise direction moving valve Beam- I33 in' theschematic draw- 59 of Figure 1 through rod 60 in a valve closingdirection decreasing the intake manifold pressure until the valve I03 isreturned to a neutral position. An opposite effect is of course producedupon the intake manifold pressure dropping below the selected value.

Pressure selecting mechanism As shown in Figures 2a and 3 pressureselector cam I36 is rigidly keyed to a pilots control shaft 4.Contacting the contour of the selector cam I36 is a cam follower I31projecting from a follower lever I38. The follower lever I38 is loadedby an extension spring I39 and pivotally mounted on a selector plate I40at pin MI. The selector plate I40 is pivoted on a pin I42 which projectsfrom a portion I43 of the control unit A.

An adjusting screw I45 is mounted on the selector plate I40 and limitsthe clockwise rotation of lever I38. The selector plate I40 pivoted onthe pin I42 transfers adjustment thereof to the whifilletree I35 throughan interconnecting pin I46 projecting from the plate I 40 and upon whichthe whiflletree beam I35 is pivotally mounted. It will be readily seenfrom the foregoing that with spring I39 pivoting lever I33 at followerI31 in a clockwise direction into contacting relation with adjustmentscrew I45, the lever I38 and selector plate I40 act as a unit, and thepressure selection of cam I36 is transmitted to the bellows and valvelinkage through pin I 40, beam I35 and pin I34.

The manifold pressure bellows I26 is provided with the adjustable lockout stop pin I25 previously described. The latter pin IE8 is adjusted toa low manifold pressure value below the minimum idling pressure for theengine 26, but above the minimum selected pressure. When pressures areselected by the pilot through operation of the control lever I which areless than the lookout setting pressure, the control unit A is lockedinto manual operation through the joint effect of the pin I28 and I34causing the adjustment of the valve I03 upward tending to adjust thethrottle valve 59 to a closed position. Thus through appropriate manualadjustment of the control lever I, the throttle 59 may be manuallycontrolled. The lockout stop I28 also permits closing of the throttle 59in the event of a broken evacuated bellows, since it provides means forplacing the control unit into manual operation.

Economy lever control The economy control, as described and claimed inthe copending divisional application Serial No. 129,132, filed November23, 1949 by Robert Z. Hague and Howard A. Alexanderson and assigned toBendix Aviation Corporation, includes a pilots economy control leverindicated in Figure 1 by the numeral I50. The latter lever I56 isconnected through a rod II to a control arm I52 keyed to the shaft 96previously described and shown in Figure 2a. Keyed to the shaft 96 is anarm I53 connected by link I54 to a bell crank I55 freely rotatable onthe shaft 4.

The bell crank I55 has a stud I56 projecting therefrom and arranged sothat when the economy control lever I50 is rotated so as to move the armI52 in a counter-clockwise direction to the cruise position, the economybell crank I55 is rotated clockwise so that during operation in thecruising range of power stud I56 will raise lever I38 increasing theselected pressure setting and stud I 56 will replace follower I31 as thepivot for the lever I38.

As the pilots control shaft 4 is rotated in a counter-clockwisedirection towards closed throttle, the cruise pressure setting must bereduced at an appropriate point and the pressure setting brought down tothe normal selection. In order to effect the latter operation a collarI60 is keyed to the shaft 4 having an adjustable screw I GI arranged soas to contact an end I62 of a lever I63 freely rotatable on the shaftI64 so as to limit the rotation of lever I 63 in a clockwise direction.Thus as shaft 4 is rotated in a counter-clockwise direction towardsclosed throttle, lever I63 is moved by screw I 6I at a predeterminedadjusted position of the shaft 4 in a counter-clockwise direction so asto apply a load to the selector plate I 40 through a pin I64 projectinfrom the plate I40. As the shaft 4 is adjusted further towards closedthrottle position, the plate I40 is adjusted in a clockwise directionabout the pivot pin I 42 so as to effectively reduce the selectedpressure a the control shaft 4 is rotated towards closed throttleposition.

When economy control lever I52 is rotated clockwise to the magneto checkposition, stud I56 contacts an upper projection of selector plate I 40,

causing the selector plate I40 to move in a clockwise direction andeffectively locking the pressure selection at a low value andmaintaining the throttle at its minimum position for purposes ofchecking the magneto. The economy control feature is claimed broadly inthe copending application Serial No. 581,878, filed March 9, 1945, byHoward A. Alexanderson and Harold A. Wheeler and assigned to BendixAviation Corporation.

Altitude correction droop mechanism In the present invention there isprovided an altitude correction device or droop mechanism shown inFigure 2. The altitude droop mechanism serves in the single stagesupercharger system disclosed (where no intercooling is provided) toprevent detonation at high altitude due to high fuel mixturetemperature. At sea level a given supercharged intake manifold pressuremay not 7 cause detonation due to its relatively lower temperature,while at relatively higher altitudes the same supercharged intakemanifold pressure may have a relatively higher temperature. The altitudedroop mechanism reduce the selected manifold pressure with increase ofaltitude to within a safe operating range. Thus at high selectedmanifold pressures drooping in the selected intake manifold pressure isstarted at relatively low altitudes and the manifold pressure setting isdecreased rapidly with change in altitude.

As lower manifold pressures are selected, drooping in the intakemanifold pressure starts at a higher altitude and occurs at a slowerrate until at low manifold pressures no correction or droop is requiredand constant manifold pressure control is provided.

The foregoing operation is effected through a bellows assembly includingan altitude bellows I15 opposed by an evacuated bellows I1I including aninternal spring I12. The bellows I10 is connected through a conduit I13to the atmospheric or scoop pressure at the inlet to the conduit 56 asshown in Figure 1.

The position of the plate I14 between the bellows I10 and HI is anindication of the air inlet or scoop pressure which varies with changesin the altitude of the aircraft and prevailing atmospheric pressure.This indication is transmitted by a lever I15 pivotally supported at I16and connected at one end to the plate I14 and at the opposite end to aplunger 1T7. The plunger 111 is slidably mounted in a supporting bearingI78 A second lever S82 is pivotally supported on a fixed pivot I33. Atone end of the lever I82 there is provided a sleeve like hearing itsformed integral therewith and a pin I85 projecting through said bearing18d and rotatably connected at one end to the lever I82.

The opposite end of the pin 1'85 affixed to a follow-up lever !85 andtransmits its motion to the selector whiifletree beam I35 through a linkI81 pivotally connected at one end to the followup lever i853 and at theopposite end to the beam Lever I82 is spring loaded in a clockwisedirection by a spring i953 which in actual practice may be in the formof a torsion spring about .pin M33. The movement of the lever 82 in aclockwise direction is limited by a pin lSI. The cam lever I19 transmitsits motion to lever {82 through a pin I92 which is formed as an integralpart of a link I933. The pin 192 may be adjusted along the surface ofthe cam. lever H9 and between the levers H9 and it? from a pointcoinciding with pivot pin 185 to a position at the left thereof. In theformer position it will be readily seen that since the pin I92 of linkI93 would be rotated at the pivot IBil of the cam lever I193 that motionof the altitude bellows 'couldnot transmit any motion to lever I82.However as the pin I82 is adjusted to the left of pivot 12scorrespondingly greater movement will be imparted .to lever in.

In order to eflect the latter adjustment of the pin i92 thelinlr I93 ispivotally connected to one end of a cam follower arm I95 pivoted on afixed pin I95 and bearing at the opposite end upon the surface of a camI97 keyed to the main control shaft 5 under the biasing force of aspring 195A which in actual practice maybe in the form of .a torsionspring about the pin 1 EB It will be seen from the foregoing that .asthe altitude correction cam id? is rotated clockwise the 'cam followerlever 595 is pivoted at pin I96 so as to move link E93 and accordinglypin lilZ into a position where the adjustment of cam lever H9 can betransmitted to lever i232. The cam shape provided at the upper surfaceof cam lever i it? determines the altitude at which motion will betransmitted to the lever I32 for manifold pressure setting. The shape ofthe cam lever is so arranged that the reater the intake manifoldpressure the lower the altitude at which correction is effected and thatat very low pressure settings no altitude correction is effected.

The feature of the altitude correction droop mechanism is described andclaimed in the copending divisional application Serial No. 111,896,filed August 23, 1949, by Howard A. Alexander-son and Robert .Z. Hagueand assigned to Bendix Aviation Corporation.

Injection system As best shown schematically in Figure 1, there isconnected to the carburetor 57 a conduit 2% leading from a suitablesource of fluid fuel for the aircraft engine. There is also provided aconduit 2%! for injecting the fuel .into the induction system through anozzle 2'62. There is all) 10 further provided a conduit 263 forinjecting into the induction system through nozzle 202 a supplemental orso-called anti-knock fluid medium such as water, water alcohol or othersuitable fluid well known in the art for suppressing predetonation ofthe-engine 2.6.

The conduit 2% is connected to a suitable metering device shown indotted outline and indicated generally by the numeral 284. The lattermetering device may be of a suitable type well aznown in the art fordetermining the rate of flow of the supplemental fluid.

A conduit 28E leads to the metering device 2% from a suitable source ofsupplemental fluid indicated by numeral .206. In the conduit 2E5, thereis provided a pump indicated by numeral 2 3'? driven by a suitable powermeans not shown. pump 25? supplies the fluid medium under ressure to themetering device 2%.

A valve 253 is provided in the conduit 2B5 between the pump and meteringdevice 2% for Oh and on control of the supplemental fluid injectionsystem. The control valve 268 may be of any suitable type, but is shownherein as of an electromagnet controlled type having an electricalcontrol circuit 299 and switch all! which is preferably mounted withinthe aircraft cabin for convenient operation by the pilot.

Thus the supplemental fluid injection system may be placed in operationby the pilot closing the switch 259 so as to effect the opening of thevalve Conversely, the valve 208 may .be closed by opening the switch2H1. As shown in Figure l the latter circuit may be also closed by theadjustment of the control lever I beyond a predetermined range of forexample 63 degrees at which point a switch ZIllA shunted across theswitch Eifi may be closed by the control lever I.

A by-pass conduit 2H and relief valve 2I2 is provided for recirculatingthe fluid medium from the pump outlet to the pum inlet at such times asthe valve 298 is closed and the injection system is not in operation.

A conduit Elf-.3 is connected to the conduit -2115 between the valve 288and the metering device 204. The conduit 2!? leads into the control unitA to a pressured reset mechanism indicated in Figure 3 by the numeral 2Mand described and claimed in a cop-ending application Serial No.291,729, filed December 20, 1950, by Howard A. Alexanderson and RobertZ. Hague and assigned to Bendix Aviation Corporation.

As shown in Figure 3 the latter mechanism includes a spring loadeddifferential diaphragm 220 mounted between the casing portions 225 and222 having chambers 223 and 225 formed at opposite sides of thediaphragm 229. The chamber 223 is open to atmosphere through a port 225while the chamber ZZZ-i is open to the pressure from the fluid mediumfrom the injection system through a port into which opens the conduit2I3 leading from the fluid injection system. The diaphragm 225 isoperably connected to a pin 22'! slidably mounted in the casing portion22!.

The pin 22? bears at one end on the diaphragm 22B and at the oppositeend on a pivotally mounted arm 228 biased in an upward direction underforce of a spring 239.

Pivotally connected at 228A is a plate 23!. The plate 235 has formedtherein a longitudinally slot 222 which opens at the lower end thereof.Positioned in the slot 232 is a cam follower lSl which projects from thefollower lever #85 into the slot 232. The upper end of the followerlever '53? is pivotally connected to a plate 233 adjustably fastened toplate 23L As shown in Figure 3, the plate 233 is pivotally mounted onplate 23! at 232 and has suitable rack teeth 2S5 screw-threadedlyengaged by an adjustable screw member 236 so that the position of theplate 233 and accordingly the cam follower I 38 may be initiallyadjusted in relation to the plate 23!. As shown in Figures 2a and 3 thespring I39 is connected at one end to the upper end of follower I38 andat the other end to arm 228 so that the spring I39 during normaloperation tends to bias the follower E38 and plate 23I in acounter-clockwise direction about the pivot 228A and the cam follower I31 into contacting relation with cam I 36.

It will be readily seen from the foregoing that upon operation of thefluid injection system the fluid medium under pressure entering thechamber 224 will bias the diaphragm 22H downward actuating the lever 228in a counter-clockwise direction. The latter action will cause the plate23I to be forced downward in a clockwise direction shifting the camfollower 31 away from the cam [36 and thereby increasing the pressuresetting of the bellows I26 to a predetermined value during operation ofthe injection system.

The plate 23l includes a cam surface 246 which is so arranged that uponadjustment of the control lever to within the range for operation of thefluid injection system a pin 241 projecting from the cam I36 may contactthe cam surface 248 and by appropriate adjustment of the control shaft 4further increase the pressure setting of the unit during operation ofthe water injection system. The follower I38 being adjusted during thelatter operation by the pin 24! acting upon the cam surface 240 so as toadjust the plate M in a counter-clockwise direction about the pin I42through the follower I 38 and thereby increase the pressure setting ofthe bellows I2! and I26.

Supercharger speed control As the valve IE3 is adjusted by the bellowsassembly from its neutral position there is effected a correspondingadjustment of the piston 64 shown in Figure 21). As the bellows callsfor greater pressure the piston 64 is adjusted upward until the throttle59 has been adjusted to the fully open position. Piston S6 is of such asize that the same eifectively overcomes all throttle loads at apredetermined fluid or oil pressure differential of for example 20 p.s. 1. When the piston 54 has opened the throttle 59 fully, if themanifold pressure still remains less than the setting, the fluidpressure differential from passage 61 to 66 will rise above thepredetermined pressure value.

A metering piston-valve 250 is provided slidably mounted in a pistonchamber 25! opening at one end into the chamber 65 and so arranged thatthe fluid pressure medium applied to the piston 64 through passage 61may be also applied to one side of a piston head 252. The piston valve25!) includes the valve members 253 and 254 and valve stem 255connecting the same. A passage 255 extends through the valve stem 255and opens at opposite sides of the valve member 253. A spring 251 biasesthe piston-valve assembly 258 upward. A pin 253 projects downward fromthe valve 25:! and is slidably mounted in a sleeve member 259. Themember 259 is screw threadedly engaged in a portion 268 of the controlunit A and is arranged so as to limit the upward movement of the pistonvalve 252. Mounted within the sleeve member 259 is a stem 2S1 having anut portion 262 screw-threadedly engaging a screw 263 locked 12 fromrotation by a portion 254 engaged in the member 259. The stem 263 isengaged at the outer end by nuts 265 so that the same may be readilylocked in adjusted position. There is formed in the outer end of thestem 25! a cleft 266 for adjustment purposes.

By appropriate adjustment of the member 259 and screw 263 the limits ofmovement of the piston valve 258 may be readily determined.

The valves 253 and 254 are arranged to open in sequence the passages21!) and 211 to pressure medium supplied the valve 250 through pressureconduit 212 as the pressure supplied the chamber 65 through passage 61exceeds predetermined differential values above the pressure suppliedthe opposite end of the valve through a passage 215, which as will belater explained equals the pressure in line 66.

The passage 218 opens into a conduit 216 which as shown in Figure 1supplies fluid medium to the low speed coupling 5I through passage 54and valve 54A. Similarly the passage 21I opens into a conduit 21? so asto supply fluid medium to the high speed coupling 39 through passage 43.

The hydraulic couplings 5| and 39 serve to couple the driving member 39to the driven member 21 at varying speed ratios depending upon the rateof fluid flow supplied to the individual cou pling which thus determinesthe slippage of the coupling and its speed ratio.

The metering piston-valve 25B is adjustably positioned by the aforenoteddifferential pressure so as to properly control the coupling ratio andaccordingly the driving speed of the supercharger 32 so as to maintain apreselected intake manifold pressure in the conduit 58 as controlled bythe servo-valve I23. By appropriate adjustment of the members 259 and26I' the minimum opening of the low speed passage 210 and the maximumopening of the high speed passage 21I may be conveniently adjusted.

In order to provide a substantially constant pressure in the passage 212there is provided a reducing valve 280 including a valve chamber 28! i 7having a pressure inlet passage 282 leading from the piston chamber BIand opening in the chamber 28| at a point between parts 283 and 284 ofthe valve 280. A spring 285 biases the valve 280 in an upward directiontending to counterbalance the pressure applied at the upper end of valve289 through a passage 286, while the valve portion 3 tends to open thepassage 212 to the pressure medium as the valve 288 is biased upward bythe spring 285 so as to increase the pressure applied through passage286 to a predetermined constant value. The tension of spring 285 may beadjusted by means of a suitable adjusting mechanism 281 so as to varythe maximum flow through passage 21!].

It has been found, however, that there is considerable variation in theback pressure in lines 218 and 2' thereby causing a metering error.Novel means to correct this condition, as described and claimed in thecopending divisional application Serial No. 111,896, filed August 23,1949, by Howard A. Alexanderson and Robert Z. Hague, include a shuttlevalve 290 provided to connect the pressure in the passage 210 to thelower end of the valve chamber 28% during low speed superchargeroperation and the pressure in the passage 21f to the lower end of thevalve chamber 28! during high speed supercharger operation. Thus as backpressure increases the Valve 282 will tend to increase the opening of'13 the passage 212 so as to compensate for such increase.

The shuttle valve 290 is slidably mounted in a valve chamber 29! andincludes a stem portion 292 having valve portions 293, 294 and 295mounted thereon in spaced relation. A passage 296 extends longitudinallyin the stem. One end of the passage 299 opens through the end of thestem 292 into the chamber 23l While the opposite end opens through theside of the stem 292 into the space between the valve portions 294 and295. The passage 210 opens into the valve chamber 29l at the left of theshuttle valve so that the pressure in the passage 210 together with theforce of a spring 29! biases the shuttle valve in the chamber 29ltowards the right. At the opposite end of the shuttle valve 290 thepressure passage 2l2 opens into the valve chamber so as to normallycounterbalance the force exerted by the spring 291 and fluid medium frompassage 210 and position the valve 250 as shown in Figure 2b.

In the latter position a passage 298 leading from the lower end of thevalve chamber 28! opens into the valve chamber 29! between the valvemembers 29:! and 295 so that the passage 210 is connected throughpassages 293 and 298 to the lower end of the reducing valve 280. Therefurther opens into the valve chamber 2% the passage 21! which opens at apoint between valve members 293 and 234 so that in the latter adjustedposition of the throttle valve the passage 2' is disconnected from thevalve 230.

However, when the pressure in passage 210 exceeds a predetermined valuethe valve 290 is shifted to the left so as to close passage 293 topassage 298 and open passage 2% to passage 2'" so as to shift thereference pressure for the reducing valve 280 from that in passage 213to the pressure in passage 2'.

After the pressure medium has been supplied the high speed coupling 39through passage 210 and 39 starts to over drive the low speed couplingthe low speed fluid feed line 54 is closed through operation of therotary valve 54A permitting the coupling 5| to empty. Upon the rotaryvalve 54A closing the low speed pressure line 54, the pressure inpassage 2W increases to a value sufiicient to cause the shifting of theshuttle valve 2% previously described and the fluid pressure in thepassage 279 maintains the shuttle valve 290 in the latter shiftedposition until such time as the high speed drive operation isterminated.

If desired a separate throttling valve may be provided for each flowcontrol port. In this way a constant differential can be provided at themetering port feeding passage 2733 and similarly a constant pressuredifferential can be supplied across the port feeding passage 21!. Thethrottling may be provided either by throttling the fluid mediumentering the metering valve or by feeding engine oil pressure into themetering valve and throttling the flow through passage 210 or 27! asrequired.

Follow-up mechanism 'When valve 253 is moved from one position toanother, there is an elapse of time required to flow the fluid mediuminto the hydraulic coupling 39 or 55 to bring the coupling to the par-14 shown in Figure-2a, has beenprovidediinr-tho hydraulic, circuit ofthe metering valve 250.

The follow-up mechanism 300 includes: avalve chamber 300A in which thereis slidably mounted an adjustable valve-piston 301. Extendinglongitudinally in the valve-piston 30!, is a passage 332 having avalveopening 303 at the upper end.

The valve opening 303 is controlled bya valve member 304 mounted on astem 305 extending longitudinally through the passage 302 and fixedlymounted at opposite ends of the valve chamber 39!. There is provided aslight, clearancebetween the defining surface of the valve opening 303and the valve member 304 sufficient to permit a limited passage of thefluid medium or oil. .Thestem 305, as shown in Figure 2a,. is positionedin spaced relation to the inner surface of the passage 302 so as topermit passage of the pressure medium such as oil upon opening of thevalve opening 303.

The follow-up valve-piston 305 is centeredby the action of a spring 303which bears at oneend upon an annular plate 331 slidably mounted within;a portion of the valve chamberrandvengaging a shoulder 398 formed on thevalve 30!. Movement ofv the plate 337 is limited by another shoulderformed within the valve chamber. The opposite end of the spring 306bears uponla similar annular plate 309 slidabl'y mounted withinaaportion of the valve chamber but similarly-limited by a shoulder portionformed within the valve chamber. The plate 309 is engaged by'a nut 3 l0provided at the lower end of the -pistonvalve 3M. The annularplates 301and 308 are slidably mounted on the piston valve 30I and are biased inopposite directions into engagement with the shoulder 308 and nut 310respectively.

An annular recess 3! i is formed in the pistonvalve 300 and opening intothe valve, chamber 300A at a pointadjacentthe recess is the. fluidpressure passage 82. Passages 210 and 211- also open intothe valvechamber but are closed by the piston-valve 300 upon the samebeingpositioned in the neutral position shown in Figure 2a.

Opening at opposite ends of the valve chamber 303A are the passages 66and 215. The passage leads from the servo valve 103 while the passage2'l5leads from the lower endof the metering valve-250 as previouslyexplained.

The amount of follow-up action effectedbythe mechanism 330 is determinedby the speed of movement of the metering valve 250, since the. uantityof fluid-medium or oil fiowingthrough the lines 63 and 215 to and fromthe follow-up mechanism is determined by the displacement-oi themetering valve 259. The follow-up piston,- valve 30! is biased to aneutral position bytthe action of spring 306 so that when metering valve259 moves downward, follow-up piston-valve 301 due to the pressureacting on theloweriend thereof moves upward and upon valve 25!? movingvupward the follow-up piston-valve 30! movesdownward.

When the follow-up piston-valve '33! reaches a maximum permissibletravel, the fluid medium or oil .is by-passed through valve opening 303which is opened by valve member 304.

During operation when only partial movement results, the oil isby-passed through the clear-- ance between the surface defining thevalve opening 393 and the valve member 3% allowing the follow-up pistonvalve 301 to be returned to .a neutral position underthe biasing. force.of spring 303. s". When a great increase'in the intake manifold pressureis required, the metering valve 250 will be subjected to a high pressuredifferential by the servo valve I83 and the metering valve will movedownward rapidly causing the follow-up piston-valve 395 to move upwardto its full extent. The latter action will not only open valve 303 butwill also open the ports in the valve chamber 309A leading to thepassages 21B and 2' to the pressure medium supplied the valve chamber300A by passage 82 so as to permit the pressure medium to be valved intothe high and low speed coupling passages 21B and 2H respectively toprovide acceleration of the couplings 39 and 5 I.

The follow-up action of the iston-valve 3EJI is transmitted by links 3I5to follow-up lever I86. Follow-up lever I85 is pivotally supported bypin I85 which is freely rotatable in the tubular member HM and leverI32. The follow-up lever I36 has the link I81 eccentrically connectedthereto so as to transmit the motion of the follow-up lever I85 to theselector whiifietree beam I35. Thus upon the metering valve 25!! movingdownward to increase the manifold pressure the followup piston valve 36Imoves upward causing the follow-up lever I86 to move in a clockwisedirection about the pin I85 and moving the whiiiletree selector beam Iin a counter-clockwise direction about the pin I46 so as to decrease thepressure setting. Likewise upon the metering valve 250 moving in anupward direction to decrease the manifold pressure the follow-up leveris moved so as to increase the pressure setting and thereby providingnovel follow-up action for preventing instability of the control unit A.

Operation the propeller governor pulley I! through a linkage mechanism 5and positions the pulley I I mechanically to the required speed setting.At the same time a cam I36 sets the pressure controlling element I33 tothe desired intake manifold pressure, while a second cam I95 sets thealtitude droop mechanism I10 so as to correct for droop in such intakemanifold pressure due to change in the altitude of the aircraft. Furthera linkage positions the throttle 59 through operation of the throttleservo valve I93 and piston 54 l to a predetermined open position.

In the automatic operating range of the unit (above the idling pressurerange determined by bellows stem I 28) the throttle opening will not besuihcient to provide the manifold pressure selected. Consequently thethrottle actuating servo 64 automatically opens the throttle 59 furtherto give the selected pressure. A a given position of the main controllever 3 the pressure and engine speed will be kept constant within thelimitations of altitude and the variations provided by the altitudedroop mechanism Iii Thus the main control lever 3 provides correlatedselection of manifold pressure and engine speed.

The cruise override control I52 permitsvariation of the manifoldpressure selection in the cruising range of pressures to provide maximumfuel economy for long range cruising. When the cruise override bellcrank I is moved in a counter-clockwise direction, the pressureselection throughout the entire movement of the pilots control is setbelow a predetermined value. This serves to lock the unit into manualoperation through the effect of the limit stem I28 so as to permitground checking of magnetos and reduction of selected pressure in anemergency, where it is desired to keep engine speed selection to a highvalue.

The engine power control A is arranged for operation with a variablespeed supercharger drive including high and low speed hydraulic drives39 and El respectively. The engine power control provides automaticcontrol of the drive by operation of a flow control valve 25G. Inmaintaining automatic control of the manifold pressure when the throttle59 reaches the wide open position, the flow control valve 258 isadjusted by increased hydraulic pressure so as to cause the superchargerspeed to increase until the selected manifold pressure is reached.

Further the control is provided with a novel device 2 I 5 for resettingthe selected intake manifold pressure upon operation of the fluid injection system controlled by the position of the pilots control lever I.Through the latter novel control dry operation may be maintainedthroughout a predetermined operating range of lever I of, for example,from 0 to a 63 angular position of the pilots lever I. Within a secondpredetermined range cf for example from 63 to 72 the throttle levercloses a switch 219A elfecting operation of the injection system. Duringthe latter operation the intake manifold pressure setting is increasedto a predetermined value which may be adjusted by adjusting the lever Iwithin the second predetermined range. However, in the event ofinjection fluid pressure or supply failure the intake manifold pressureis automatically reset to the maximum dry rating through operation ofthe device 2 I 5.

It should be further noted that when hydraulic pressure is available,the throttle is positioned by the hydraulic servo piston 64 even in themanual range.

Thus upon manual adjustment of the shaft 4 in a counter-clockwisedirection past a predetermined critical low pressure setting position,the cam I 36 positions the pin I34 so that the valve stem I83 is raisedabove its neutral position, while the pin I 28 locks the bellows I26 outof operation in a pressure decreasing direction and is thus ineffectivefor returning the valve stem I93 to a neutral position.

The latter upward adjustment of the valve stem I03 opens port 56 to thepressure medium supplied through line 82 so that pressure is applied topiston 64 at the upper side tending to move piston 64 in a downwarddirection and actuating arm 69 in a counter-clockwise direction. Suchcounter-clockwise movement of arm 69 adjusts throttle arm GI in athrottle closing direction and acts through interconnecting linkages I3,12 and II so as to move arm is in a clockwise direction and therebyactuate the plunger I00 downward to return the valve stem I 03 to aneutral position.

Further manual adjustment of the shaft 4 and the arm '10 in acounter-clockwise direction causes the arm 74 to be moved in acounter-clockwise direction so that plunger I releases valve stem I03whereupon leaf spring I04 raises the same so as to permit the pressuremedium to be applied to the upper side of piston 64 causing furthercounter-clockwise movement of the arm 69 so that the arm 14 once moreresets the valve stem I03 to a neutral position and effects furtheradjustment of the throttle arm Si in a valve closin direction.

Of course upon manual adjustment of the arm if! within the automaticlock out range in a clock- Wise direction, there will be effected aclockwise movement of arm M past the critical neutral position causingvalve stem 03 to be lowered whereupon t t will actuate arm as in aclockwise direction moving arm it in a counterclockwise direction sothat the valve stem 593 will be returned to a neutral position and thethrottle arm 55 adjusted in a valve opening direction. Upon the shaft abeing adjusted in a clockwise direction past the limit of the automaticlock out range, the mechanism will once again be placed in automaticoperation controlled by the pressure selector cam 56.

In the event of a hydraulic pressure failure the novel manually operablemechanical linkage iii, 7!, l2, l3 and "id is arranged so as to providedirect manual throttle control as heretofore explained. This linkage isparticularly effective at the time of starting the aircraft engine. Themanual throttle travel is sufficient to give normal power at tfisub'Ofiengine speed at sea level.

During normal operation of the engine cruise override control 150 willbe kept at its neutral position and both engine speed and manifoldpressure will be controlled and selected together by the single pilotscontrol lever I.

Constant manifold pressure and engine speed will be obtained at fixedpilots control lever l positions up to critical altitude except aslimited by the novel altitude droop device lit and as momentarilyeffected by the novel follow-up device Stil. The altitude droopmechanism serves to prevent the intake manifold pressure obtainedthrough the control of the supercharger speed and throttle valve fromexceeding values required for the safe operation of the engine Withoutliquid injection at the prevailing altitude of the aircraft as describedand claimed in the copending divisional application Serial No.

111,896, filed August 23, 1949, by Howard A. Alexanderson and Robert Z.Hague and assigned to Bendix Aviation Corporation.

Although only one embodiment of the invention has been described andillustrated in detail,

it is to be expressly understood that the same is not limited thereto.Various changes may be made in design and arrangement of the partsillustrated, as Well be apparent to those skilled in the art. For adefinition of the limits of the invention, reference should be had tothe appended claims.

What is claimed is:

1.. An engine control system comprising pilot controlled means forselecting a desired intake manifold pressure for the engine, a throttlevalve for controlling the intake manifold pressure, a supercharger forsupplying air to the intake manifold of the engine, a first hydraulicmotor means for positioning the throttle, intake manifold pressureresponsive means for controlling the hydraulic motor means, hydrauliccoupling means for driving the supercharger from the engine, hydraulicnow control means for regulating the flow of hydraulic medium to thecoupling means thereby the speed of said supercharger, a secondhydraulic motor means for positioning said flow control means, and saidsecond hydraulic motor means being controlled by said intake manifoldpressure responsive means so as to maintain said selected pressure.

2. An engine control system comprising pilot operative means forselecting a desired manifold pressure for the engine, a. throttle valvefor controlling the manifold pressure, manifold pressure responsivemeans for adjusting said throttle valve so as to maintain the selectedmanifold pressure, a supercharger for maintaining the manifold pressurein accordance with the selected pressure, variable speed driving meansfor said supercharger, means for controlling said variable speed drivingmeans, said control means being regulated by said manifold pressureresponsive means, and follow-up means responsive to actuation of saidcontrol means for effecting said variable speed driving means so as tocause a more rapid acceleration of said supercharger upon the selectedmanifold pressure being greatly in excess of the actual manifoldpressure.

3. An engine control system comprising pilot operative means forselecting a desired manifold pressure for the engine, a, throttle valvefor controlling the manifold pressure, manifold pressure responsivemeans for adjusting said throttle valve so as to maintain the selectedmanifold pressure, a supercharger for maintaining the manifold pressurein accordance with the selected pressure, variable speed driving meansfor said supercharger, means for controlling said variable speed drivingmeans, said control means being regulated by said manifold pressureresponsive means, follow-up means responsive to actuation of saidcontrol means for effecting said variable speed driving means so as tocause a more rapid acceleration of said supercharger upon the selectedmanifold pressure being greatly in excess of the actual manifoldpressure, and said follow-up means being arranged so as tosimultaneously actuate said pressure selecting means so as tomomentarily decrease the value of the selected manifold pressure.

4. A device of the character described, comprising, in combination, acondition responsive means, hydraulic motor means, valve means forcontrolling said motor means, resilient means operably connecting saidcondition responsive means to said valve means, a first adjustableelement, a second element adjustably positioned by said motor means,means operably connecting said first and second elements to said controlvalve means in such a manner that said elements within a limited rangemay so adjust said valve means as to override said condition responsivemeans and cause said motor means to adjust the position of said secondelement in direct relation to the adjusted position of said firstelement.

5. A device of the character described, comprising, in combination, acondition responsive means, hydraulic motor means, valve means forcontrolling said motor means, resilient means operably connecting saidcondition responsive means to said valve means, a first adjustableelement, a second element .adjustably positioned by said motor means,means operably connecting said first andsecond elements to .saidcontrolvalve means in such a manner that said elements within a limited rangemay so adjust said valve means as to override said condition responsivemeans and cause said motor means to adjust the position of said secondelement in direct relation to the adjusted position of said firstelement, and means for changing the datum of said condition responsivemeans, said datum changing means operablycontrolled by said firstadjustable element.

6. The combination defined in claim in which the means operablyconnecting said first and second elements to said control valve includesa walking beam operably connected to said first and second elements andsaid control valve.

7. An engine control device comprising a first piston, a second piston,a common pressure chamber for said pistons, means controlling thepressure applied to said chamber, said first piston being actuated in afirst sense at a predetermined pressure controlled by said means, andsaid second piston being actuated in a second sense at a greaterpredetermined pressure upon said first piston being actuated in saidfirst sense to the limit of its movement, a first member positioned byone of said pistons to adjust an induction throttle valve in the engine,and a second member adjustably positioned by the other said pistons forcontrolling the driven speed of an engine supercharger.

8. A regulator for the induction system of a supercharged aircraftengine, comprising a first piston, a second piston, a common hydraulicpressure chamber for said pistons, induction pressure responsive meansfor controlling the hydraulic pressure applied to said chamber, saidfirst piston arranged to be actuated in a first sense at a firsthydraulic pressure, said second piston arranged to be actuated in asecond sense at a greater hydraulic pressure upon said first pistonbeing actuated in said first sense to a maximum limit, a memberpositioned by said first piston to adjust an induction throttle valvefor said engine, a fioW control valve adjustably positioned by thesecond piston for controlling the flow of a fluid medium to a hydrauliccoupling drive for the engine supercharger.

9. A regulator for the induction system oia supercharged aircraftengine, comprising a first piston, a second piston, a common hydraulicpressure chamber for said pistons, induction pressure responsive meansfor controlling the hydraulic pressure applied to said chamber, saidfirst piston arranged to be actuated in a first sense at a firsthydraulic pressure, said second piston arranged to be actuated in asecond sense at a greater hydraulic pressure upon said first pistonbeing actuated in said first sense to adjust an induction throttle valvefor said engine, another member adjustably positioned by the secondpiston for controlling the driven speed of an engine supercharger, meansfor changing the datum of the pressure responsive means, and a follow-upvalve hydraulically coupled to said pistons for operating said datumchanging means so as to prevent hunting of said pressure r sponsivemeans upon change in the induction pressure.

10. A regulator for the induction system of a supercharged aircraftengine, comprising a first piston, a second piston, 21. common hydraulicpressure chamber for said pistons, induction pressure responsive meansfor controlling the hydraulic pressure applied to said chamber, saidfirst piston arranged to be actuated in a first sense at a firsthydraulic pressure, said second piston arranged to be actuated in asecond sense at a greater hydraulic pressure upon said first pistonbeing actuated in said first sense to adjust an induction throttle valvefor said engine, another member adjustably positioned by the secondpiston for controlling the driven speed of an engine supercharger, meansfor changing the datum of the pressure responsive means, a followupvalve hydraulically coupled to Said pistons for operating said datumchanging means so as to prevent hunting of said pressure responsive mans upon change in the induction pressure, and said follow-up valveindependently controlling the driven speed of said engine superchargerso as to effect an acceleration of said supercharger upon a relativelygreat increase in the induction pressure being required.

11. The combination comprising a piston slidably mounted in a pressurechamber, said pressure chamber having hydraulic pressure inlet andoutlet openings at opposite ends for efiecting movement of said piston,said piston having a longitudinal passage formed therein, said passageopening at the opposite ends of said piston, a stem mounted in saidchamber and extending through the longitudinal passage formed in saidpiston, a valve member fixedly mounted on said stem and arranged tocontrol the flow of fluid medium through said passage, said valvearranged to open said passage upon movement of said piston to one end ofsaid chamber so as to equalize the hydraulic pressure at opposite endsor" the piston, spring means for returning the piston to a neutralposition, and control means operated by said piston.

12. The combination comprising a piston slidably mounted in a pressurechamber, said pressure chamber having hydraulic pressure inlet andoutlet openings at opposite ends for eifecting movement of said piston,said piston having a longitudinal passage formed therein, said passageopening at the opposite ends of said piston, a stem mounted in saidchamber and extending through the longitudinal passage formed in saidpiston, a valve member fixedly mounted on said stem and arranged tocontrol the flow of fluid medium through said passage, said valvearranged to open said passage upon movement of said piston to one end ofsaid chamber so as to equalize the hydraulic pressure at opposite endsof the piston, a first annular plate about said piston, said piston andchamber having parts for limiting movement of said first plate in onedirection, a second annular plate about said piston, said piston andchamber having other parts for limiting movement of said second plate inan opposite direction, a spring interposed between said first and secondplates for normally biasing said plates into contacting relation withsaid parts so as to maintain the piston in a position intermediate theopposite ends of said chamher, and mechanical and hydraulic controlmeans operated by said piston.

13. An aircraft power unit comprising, in combination an internalcombustion engine, a governor to control the engine speed, an inductionthrottle valve, a supercharger, means for driving said supercharger,means for changing the driven speed of said supercharger, a regulatingdevice responsive to the induction pressure of the engine to selectivelyand progressively control said induction throttle and said speedchanging means, a master control device under the control of the pilotfor simultaneously changing the datum of the governor and the datum ofthe regulating device so as to maintain a predetermined relationshipbetween engine speed and induction pressure, and a second pilot operatedmeans alternately operable for increasing or decreasing suchpredetermined relationship between engine speed and induction pressureindependently of the operation of said master control device.

14. A device of the character described, commeans for prising,

prising manually operable means for selecting a desired engine intakemanifold pressure, a hydraulic motor means for regulating the intakepressure, intake manifold pressure responsive controlling the hydraulicmotor means, and means actuated by said manually operable means forrendering said pressure responsive means ineffective for controllingsaid motor means within a predetermined operating range of said manuallyoperable means, and said actuating means so arranged that said motormeans may be controlled directly by said manually operable means withinsaid predetermined operating range.

1-5. A device of the character described, comprising manually operablemeans for selecting a desired engine intake manifold pressure, ahydraulic motor means for regulating the intake pressure, intakemanifold pressure responsive means for controlling the hydraulic motormeans, a piston subject to the operating pressure for said motor means,spring means biasing said piston in a direction opposing said operatingpressure, means actuated by said piston upon pressure failure forrendering said pressure responsive means ineffective for controllingsaid motor means, and means interconnecting said manually operable meansto said motor means for effecting manual operation of said motor meansupon such pressure failure.

16. A device of the character described, corn.-

in combination, condition responsive means, hydraulic motor meansautomatically controlled by said condition responsive n cans foradjusting a control device, a control member for varying the datum ofsaid condition responsive means, means for limiting the control of saidmotor means by said condition responsive means upon adjustment of saidcontrol member within predetermined datum setting range, and meansoperated by said member for controlling said motor means so as toposition said control device in direct relation to the adjusted positionof said control member within said predetermined range.

17. The combination comprising a condition responsive means, hydraulicmotor means for ad justing a control device, a valve means for controlling said motor means, an adjustable control element, first meansoperably connecting said element to said condition responsive means forvarying the datum thereof, said first connecting means including meansjointly connecting said condition responsive means and said element tosaid control valve means, means for limiting the adjustment by saidcondition responsive means of said control valve means, and second meansconnecting said element to said control valve means, second connectingmeans operable Within a predetermined limited range of adjustment ofsaid element and coasting with said first connecting means and saidlimiting means so as to control said motor means in such a manner as toadjust said control de vice in direct relation to the adjusted positionof said main control element.

18. For use with an internal combustion engine having athrottle-controlled induction passage provided With a superchargingsystem in cluding a superchar er and fluid coupling means for varyingthe ratio of engine-to-supercharger speed; the combination comprisingmeans for regulating hydraulic flow of said fluid coupling including aflow metering valve, a servo piston for operative connection to saidthrottle for actuating the same and another servo piston :arranged toposition said metering valve, a servo valve controlling admission ofoperating pressure to said pistons, a device responsive to changes inmanifold pressure, means providing an operating connection between saiddevice and said servo valve whereby the throttle may be automaticallypositioned to maintain a predetermined manifold pressure up to chargingcapacity for approximateliy wide-open throttle and said metering valvethereafter regulated to produce a supercharger speed such as willmaintain the predetermined charging pressure.

19. Control mechanism for regulating the charging pressure supplied toan internal combustion engine comprising manifold pressure responsivemeans, means for changing the datum of said pressure responsive means, apiston operatively connected to the datum changing means andhydraulically coupled to said pressure responsive means, said. pistonmovable upon changes in the charging pressure so as to tend tomomentarily reset the datum changing means in a direction opposite thedirection of change in manifold pressure, said piston having ableedpassage, and spring means for returning said piston to a neutralposition upon cessation of change in said charging pressure.

20. The combination defined by claim 19 including a valve membercontrolling said bleed passage in accordance with the extent of changein the charging pressure.

21. Control mechanism for regulating the charging pressure supplied toan internal combustion engine comprising manifold pressure responsivemeans, means for chan ing the datum of pressure responsive means, andmeans hydraulically coupled to said pressure responsive means operativeduring changes in charging pressure and tending to momentarily reset thedatum changing means in a direction opposite to the direction of changein manifold pressure.

22. For use with an internal combustion engine having a throttlecontrolled induction passage provided with a supercharging systemincluding a supercharger and fluid coupling means for varying the ratioor" engine-to-supercharger speed-power control mechanism including amanually operable power control member, means for regulating the fluidflow to said nuid coupling means, hydraulic means for selectivelyoperating said throttle and fluid regulating means, said hydraulic meansincluding a first piston for operating the throttle and a second pistonforoperating said fluid regulating means, a servo valve for controllingsaid hydraulic means, variable datum means including a device responsiveto changes in manifold pressure and an element adjustable by said powercontrol member to set the datum for said device, and means providing anoperative connection between said pressureresponsive device and saidservo valve to control said hydraulic means and thereby selectivelycause said first piston to be automatically positioned to maintain theselected manifold pressure up to capacity for approximately wide-openthrottle and said fluid regulating means to be thereafter controlled bysaid second piston to provide a supercharger speed which will maintainthe required charging pressure.

'23. For use with an internal combustion engine having athrottle-controlled induction passage provided with a superohargingsystem including a supercharger and fluid coupling means for varying theratio of engine-to-supercharger speed,

power control mechanism including a manually operable control member,means for regulating hydraulic flow to said fluid coupling including ahow metering valve, a servo piston operatively connected to saidthrottle for actuating the same and another servo piston arranged toposition said metering valve, a servo valve controlling admission ofoperating pressure to said pistons, variable datum means including adevice responsive to changes in manifold pressure and an elementadjustable by said power control member to set the datum for saiddevice, means providing an operating connection. between said device andsaid servo valve whereby the throttle is automatically positioned tomaintain a selected manifold pressure up to charging capacity forapproximately wide-open throttle and said metering valve is thereafterregulated to produce a supercharger speed such as will maintain therequired charging pressure.

24. Control mechanism for regulating the charging pressure supplied toan internal combustion engine comprising variable datum means includin acapsule responsive to changes in manifold pressure, means for adjustingthe datum of said capsule, and means becoming operative during changesin charging pressure tending to momentarily reset the datum in adirection opposite the direction or" change in manifold pressure as thecharging pressure approaches the value set by said adjusting means.

25. Control mechanism for regulating the charging or manifold pressur ofan internal combustion engine comprising variable datum means includinga capsule responsive to changes in manifold pressure, means foradjusting the datum of the capsule, and means becoming operative as aresult of changes in manifold pressure and varying substantially as therate of change tending to momentarily reset the datum in a directiontoward the actual manifold pressure, causing said capsule to return toits normal or neutral position earlier and thereby prevent overshootingof the manifold pressure beyond the value set by said adjusting means.

26. In control mechanism for regulating the charging or manifoldpressure of a supercharged internal combustion engine having a throttlecontrolled induction passage, variable datum means including a capsuleresponsive to changes in manifold pressure, means for adjusting thedatum of said capsule, a servo motor for varying the position of thethrottle, a servo valve for regulating hydraulic flow to said servomotor, means operatively connecting said servo valve to said variabledatum means to be regulated thereby, and fluid pressure means adapted toprevent overshooting of the manifold pressure when the datum is changedby momentarily changing the datum setting in a direction counter to theadjustment and becoming decreasingly effective as the manifold pressureapproaches the datum setting.

27. For use with an engine having an air intake system provided with asupercharger and a hydraulic coupling for transmitting a, driving forceto said supercharger at variable ratios of engine-tosupercharger speed,a power control device including a fiow regulating or meterin valve forregulating the flow of fluid to said coupling, said valve having amember movable to diiferent positions to vary the rate of fluid flow,means for subjecting said member to an operating pressure medium, meansresponsive to changes in pressure in the air intake system forcontrolling providing fluid pressure to a control element such that thefluid pressure and the controlled element motion are proportional to thedeviation, a reset means including a piston responsive to changes insaid fluid pressure, a constant effort means applied to said reset meansso that the reset means is static whenever fluid pressure correspondingto zero deviation obtains, a flow restriction for dampin the motion ofsaid reset means, said element and said reset means cooperating toregulate the controlled variable.

29. In a control apparatus, a control element and a reset means whichcooperate to regulate the value of a controlled variable, meansincluding an expansible chamber for determining the position of saidelement in accordance with the deviation of the controlled variable froma selected value, a member sensitive to said deviation, means associatedwith said member for creating a fluid pressure difference which varieseither in a positive or negative sense with changes in the position ofsaid member on either side of a position corresponding to zero deviationof said variable, means for moving said reset means by said pressuredifference, and a flow restriction for damping the motion of said resetmeans.

30. An engine control system comprising pilot controlled means forselecting a desired intake manifold pressure for the engine, a throttlevalve for controlling the intake manifold pressure, a super-charger forsupplying air to the intake manifold of the engine, a first hydraulicmotor means for positioning the throttle, intake manifold pressureresponsive means for controlling the hydraulic motor means, hydrauliccoupling means for driving the supercharger from the engine, hydraulicflow control means for regulating the flow of hydraulic medium to thecoupling means and thereby the speed of said supercharger, a secondhydraulic motor means for positioning said flow control means, saidsecond hydraulic motor means being controlled by said intake manifoldpressure responsive means so as to maintain said selected pressure, andfollow-up means for varying the setting of said pressure responsivemeans in accordance with change in hydraulic pressure effecting saidsecond hydraulic motor means.

31. An engine control system comprising pilot operative means forselecting a desired manifold pressure for the engine, a throttle forcontrolling the manifold pressure, manifold pressure responsive meam foradjusting said throttle valve so as to maintain the selected manifoldpressure, a supercharger for maintaining the manifold pressure inaccordance with the selected pressure, variable speed driving means forsaid supercharger, hydraulic motor means for controlling said variablespeed driving means, and said controlling means being regulated by saidmanifold pressure responsive means upon said throttle being adjusted toa maximum open position, and follow-up means for varying the setting ofsaid pressure responsive means in accordance with change in hydraulicpressure afiecting said hydraulic motor means.

32. The combination defined by claim 31 in which there is provided meansfor resetting the follow-up means, and means for controlling theresetting means operated by said follow-up means.

33. A regulator for the induction system of a supercharged aircraftengine, comprising a first piston, a second piston, a common hydraulicpressure chamber for said pistons, induction pressure responsive meansfor controlling the hydraulic pressure applied to said chamber, saidfirst piston arranged to be actuated in a first sense at a firsthydraulic pressure, said second piston arranged to be actuated in asecond sense at a greater hydraulic pressure upon said first pistonbeing actuated in said first sense to adjust an induction throttle valvefor said engine, another member adjustably positioned by the secondpiston for controlling the driven speed of an engine supercharger, meansfor changing the datum of the pressure responsive means, a follow-uppiston hydraulically coupled to said second piston, means connectingsaid follow-up piston to said datum changing means so as to preventhunting of said pressure responsive means upon a change in the greaterhydraulic pressure afiecting said second piston.

34. An aircraft engine control system comprising pilot-controlled meansfor selecting a desired intake manifold pressure for the engine, athrottle valve for controlling the intake manifold pressure, asupercharger for supplying air to the intake manifold of the engine,servo motor means for positioning the throttle, intake manifold pressureresponsive means for controlling the servo motor means, a plurality ofhydraulic couplings between the supercharger and the engine, means forcontrolling flow of pressure fluid to effect selective operation of saidhydraulic couplings, said controlling means being regulated by saidmanifold pressure responsive means upon said throttle being adjusted toa maximum open position to vary the supply of pressure fluid to 26 theselected coupling so as to drive the supercharger at a speed necessaryto obtain the desired intake manifold pressure.

35. For use with an internal combustion engine having an air intakesystem provided with a supercharger and a hydraulic coupling fortransmitting a driving force to said supercharger at variable ratios ofengine-to-supercharger speed, a power control device including a flowregulating or metering valve for regulating the flow of hydraulic fluidto said coupling, means responsive to changes in the air intake pressurefor moving said valve to different flow regulating positions, means forresetting said valve to a definite flow regulating position after havingbeen initially moved, means for regulating the resetting actionincluding a bleed, and an accelerating device for accelerating theresetting movement of said valve, said device including means fortemporarily varying said bleed.

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